Bathing suits are typically made with synthetic fibers such as polyester and nylon. They're designed to stretch to the wearer's body shape without being damaged, so these fabrics are resistant to shrinking. ... As long as the suit hasn't been washed more than a few times before, the fabric may shrink noticeably.

Will a swimsuit shrink in the dryer?

If you're asking to know whether or not a bathing suit will shrink in the dryer then the answer is absolute Yes. Dryers are an excellent way to shrink your suit but then, the heat in it can cause the fibre in them to weaken so to keep your suit in the best condition, they shouldn't be used that often.

Is there a way to shrink a swimsuit?

Try using boiling hot water to soak your suit and then put it through a hot cycle in the dryer, or try ironing a damp suit on low heat to gradually shrink the material. It may require a couple of attempts, but you should be able to shrink your suit down to the size you prefer.